FCP/SCP phosphatase belongs to a family of phosphatase which uses an Asp nucleophile for catalysis. FCP/SCP is characterized by its phosphatase activity towards the CTD of the largest subunit of RNA polymerase II (1). At least seven members have been identified in human genome and FCP/SCP phosphatases share a conserved catalytic signature, which is known as DXDXT/V (2). Family member FCP1 is conserved among all eukaryotes and plays an important role in cell survival in budding and fission yeasts. SCP1 preferentially dephosphorylates Ser5 in CTD domain of RNA polymerase II and plays a role in the regulation of gene expression by controlling the transition from initiation/capping to processive transcript elongation (3). In addition, SCP1 also acts as a key regulator that functions in silencing neuronal gene expression (4).

Reference
1. Shi, Y. (2009) Serine/threonine phosphatases: mechanism through structure. Cell, 139, 468-484. PMID: 19879837
2. Moorhead, G.B., Trinkle-Mulcahy, L. and Ulke-Lemee, A. (2007) Emerging roles of nuclear protein phosphatases. Nat Rev Mol Cell Biol, 8, 234-244. PMID: 17318227
3. Yeo, M., Lin, P.S., Dahmus, M.E. and Gill, G.N. (2003) A novel RNA polymerase II C-terminal domain phosphatase that preferentially dephosphorylates serine 5. J Biol Chem, 278, 26078-26085. PMID: 12721286
4. Yeo, M., Lee, S.K., Lee, B., Ruiz, E.C., Pfaff, S.L. and Gill, G.N. (2005) Small CTD phosphatases function in silencing neuronal gene expression. Science, 307, 596-600. PMID: 15681389